Many current satellite receiving systems employ a low noise block converter with a feed (“LNBF”) to tune a satellite dish in order to receive broadcast signals at a set-top box. Oftentimes, a local oscillator circuit supplies a base tuning frequency for the LNBF and dish. The local oscillator may be, for example, a dielectric resonator oscillator (“DRO”).
Over time, a DRO's base tuning frequency may drift due to age or temperature. When drift occurs, the perceived frequency of any broadcast satellite signal, as measured by a demodulator associated with a set-top box in communication with the LNBF, no longer matches the actual frequency of the broadcast. Accordingly, to the demodulator, dish and any attached equipment like a set-top box or digital video recorder, a desired transponder signal may appear to be lost when in fact the demodulator is erroneously searching for it (or tuning to it) at the wrong frequency.
In addition, such drift may be difficult to diagnose because it may be intermittent. For example, certain DROs experience excessive drift only when their operating temperature exceeds a threshold. Thus, the drift of a DRO may be sufficiently large to remove a satellite signal from a frequency band searched by the system only if the ambient temperature is over the threshold. For example, if the temperature is sufficiently cool, the drift may be low enough that the satellite signal is within the searched frequency band and therefore acquired during normal system operation. This may lead to intermittent loss of a satellite signal only on particularly hot days or afternoons, for example. It should be noted that drift may be exaggerated by either heat or cold. The transient nature of such signal loss may make it difficult to diagnose and fix such a channel loss.